The typical modern automotive vehicle includes a mechanism for equalizing the pressure between the interior compartment of the automobile and the outside atmosphere. The interior or passenger compartment of the vehicle is effectively sealed from the outside atmosphere, thus providing good heating and air conditioning within. Under certain operating circumstances, air pressure in the passenger compartment may exceed ambient atmospheric pressure. This condition typically arises when a door is closed when an occupant enters or exits the vehicle. If the interior is not vented to the atmosphere to equalize pressure, it is likely that the effort required to close the door will increase. Under this circumstance, the occupant will need to exert greater effort to move the door.
Efforts have been made to overcome this problem and have been employed in the construction of vehicles. A common solution has been the provision of an air extractor as a pressure responsive device interposed between the passenger compartment and the exterior of the vehicle. An air extractor is a one-way valve that allows air to move from the inside of the vehicle to the outside without letting in the outside air.
An example of a known air extractor is shown in FIG. 1. With reference to that figure, a conventional air extractor, generally illustrated as 10, is shown. The air extractor 10 includes a body 12 having air passages 14, 14′ and 14″ formed therein. Over each air passage is provided a pivotable flap. Accordingly, a flap 16 is hingedly attached to the body 12 over the air passage 14, a flap 16′ is provided over the air passage 14′, and a flap 16″ is provided over the passage 14″. Variations of this arrangement are known but the air extractor 10 shown in FIG. 1 is exemplary.
While providing advantages to vehicle design and operation there are several drawbacks to known air extractor designs. First, the flaps of the typical air extractor are controlled by gravity and are thus are limited in their installed orientation to a vertical orientation. The flaps of the typical air extractor are also controlled by air flow. Therefore, the flaps do not stay closed when they should due to many circumstances, including the position of the vehicle on the underlying surface, the motion of the vehicle and the vibration of the vehicle. It is not possible to control gravity or air flow without physical shape modifications.
Second, air flow rate of the known air extractor is related directly to flap design, sizing and area. According to current designs not one of these variables is controlled.
Third, the flaps make noises that may be audible to the vehicle occupants when they open or close.
The fourth drawback is also related to noise. As known air extractor designs represent a compromise between the need to exhaust air out of a vehicle and the desire to limit the amount of noise in the vehicle, the result is that the size of the air extractor is reduced to a minimum thus keeping the noise entering the vehicle to a minimum. On the one hand, noise is reduced but, on the other hand, air flow is also necessarily reduced.
Fifth, the body and flap construction of known air extractors requires several independently moving parts and is thus complex and expensive.
Accordingly, as in so many areas of vehicle technology, there is room in the art of air extractor technology for an alternative configuration that provides maximum effective air flow with minimal vehicle noise and operating parts.